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Recombination in vaccine and circulating strains of porcine reproductive and respiratory syndrome viruses.

Li B, Fang L, Xu Z, Liu S, Gao J, Jiang Y, Chen H, Xiao S - Emerging Infect. Dis. (2009)

Bottom Line: Em2007, a porcine reproductive and respiratory syndrome virus (PRRSV) variant with a unique 68 aa deletion in Nsp2, was recently isolated in China.Phylogenetic and molecular evolutionary analyses indicated that Em2007 is a natural recombinant between a vaccine strain of PRRSV and circulating virus.We also tested its pathogenicity in piglets.

View Article: PubMed Central - PubMed

Affiliation: Huazhong Agricultural University, Wuhan 430070, People's Republic of China.

ABSTRACT
Em2007, a porcine reproductive and respiratory syndrome virus (PRRSV) variant with a unique 68 aa deletion in Nsp2, was recently isolated in China. Phylogenetic and molecular evolutionary analyses indicated that Em2007 is a natural recombinant between a vaccine strain of PRRSV and circulating virus. We also tested its pathogenicity in piglets.

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Related in: MedlinePlus

Pathogenicity comparison among the Em2007, CH-1a, and WUH1 strains of porcine reproductive and respiratory syndrome virus (PRRSV). Forty-day-old piglets (9 piglets in each group) free of PRRSV were inoculated intramuscularly with 105.0 mean tissue culture infectious doses/2 mL of Em2007, CH-1a, WUH1, respectively. Two piglets from each group were euthanized and necropsied at 7 and 10 days postinoculation (dpi) for viral load analyses and histopathologic examinations. The remaining 5 piglets in each group were used to evaluate rate of death. Mean rectal temperature (A) and survival rate (B) of each group were recorded for 21 dpi.
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Figure 2: Pathogenicity comparison among the Em2007, CH-1a, and WUH1 strains of porcine reproductive and respiratory syndrome virus (PRRSV). Forty-day-old piglets (9 piglets in each group) free of PRRSV were inoculated intramuscularly with 105.0 mean tissue culture infectious doses/2 mL of Em2007, CH-1a, WUH1, respectively. Two piglets from each group were euthanized and necropsied at 7 and 10 days postinoculation (dpi) for viral load analyses and histopathologic examinations. The remaining 5 piglets in each group were used to evaluate rate of death. Mean rectal temperature (A) and survival rate (B) of each group were recorded for 21 dpi.

Mentions: Results showed that piglets inoculated with CH-1a experienced only temporary fever and mild respiratory symptoms. Obvious clinical signs, including inappetence, lethargy, high and continuous fever, red discolorations in the body, and blue ears were observed in piglets inoculated with WUH1 (Figure 2, panel A). Furthermore, severe interstitial pneumonia (Technical Appendix) and nonsuppurative encephalitis cases were also observed 7 and 10 days postinoculation (Figure 2, panel B). Four of 5 piglets died within 21 days after inoculation. Piglets inoculated with Em2007 also showed similar clinical signs to those seen in the WUH1 group. However, the interstitial pneumonia and nonsuppurative encephalitis were mild and no deaths occurred throughout the experimental period in Em2007 group. The results of viremia and viral load also indicated that Em2007 was more mild than WUH1, but of substantially higher virulence than CH-1a (data not shown).


Recombination in vaccine and circulating strains of porcine reproductive and respiratory syndrome viruses.

Li B, Fang L, Xu Z, Liu S, Gao J, Jiang Y, Chen H, Xiao S - Emerging Infect. Dis. (2009)

Pathogenicity comparison among the Em2007, CH-1a, and WUH1 strains of porcine reproductive and respiratory syndrome virus (PRRSV). Forty-day-old piglets (9 piglets in each group) free of PRRSV were inoculated intramuscularly with 105.0 mean tissue culture infectious doses/2 mL of Em2007, CH-1a, WUH1, respectively. Two piglets from each group were euthanized and necropsied at 7 and 10 days postinoculation (dpi) for viral load analyses and histopathologic examinations. The remaining 5 piglets in each group were used to evaluate rate of death. Mean rectal temperature (A) and survival rate (B) of each group were recorded for 21 dpi.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3044526&req=5

Figure 2: Pathogenicity comparison among the Em2007, CH-1a, and WUH1 strains of porcine reproductive and respiratory syndrome virus (PRRSV). Forty-day-old piglets (9 piglets in each group) free of PRRSV were inoculated intramuscularly with 105.0 mean tissue culture infectious doses/2 mL of Em2007, CH-1a, WUH1, respectively. Two piglets from each group were euthanized and necropsied at 7 and 10 days postinoculation (dpi) for viral load analyses and histopathologic examinations. The remaining 5 piglets in each group were used to evaluate rate of death. Mean rectal temperature (A) and survival rate (B) of each group were recorded for 21 dpi.
Mentions: Results showed that piglets inoculated with CH-1a experienced only temporary fever and mild respiratory symptoms. Obvious clinical signs, including inappetence, lethargy, high and continuous fever, red discolorations in the body, and blue ears were observed in piglets inoculated with WUH1 (Figure 2, panel A). Furthermore, severe interstitial pneumonia (Technical Appendix) and nonsuppurative encephalitis cases were also observed 7 and 10 days postinoculation (Figure 2, panel B). Four of 5 piglets died within 21 days after inoculation. Piglets inoculated with Em2007 also showed similar clinical signs to those seen in the WUH1 group. However, the interstitial pneumonia and nonsuppurative encephalitis were mild and no deaths occurred throughout the experimental period in Em2007 group. The results of viremia and viral load also indicated that Em2007 was more mild than WUH1, but of substantially higher virulence than CH-1a (data not shown).

Bottom Line: Em2007, a porcine reproductive and respiratory syndrome virus (PRRSV) variant with a unique 68 aa deletion in Nsp2, was recently isolated in China.Phylogenetic and molecular evolutionary analyses indicated that Em2007 is a natural recombinant between a vaccine strain of PRRSV and circulating virus.We also tested its pathogenicity in piglets.

View Article: PubMed Central - PubMed

Affiliation: Huazhong Agricultural University, Wuhan 430070, People's Republic of China.

ABSTRACT
Em2007, a porcine reproductive and respiratory syndrome virus (PRRSV) variant with a unique 68 aa deletion in Nsp2, was recently isolated in China. Phylogenetic and molecular evolutionary analyses indicated that Em2007 is a natural recombinant between a vaccine strain of PRRSV and circulating virus. We also tested its pathogenicity in piglets.

Show MeSH
Related in: MedlinePlus